This invention relates to prosthetic devices. In particular it relates to a prosthetic device which may form a portion of a lower limb prosthesis. The device allows incremental rotation in the transverse plane of the inferior portion of the lower limb prosthesis.
In fitting a patient with a prosthesis following amputation of a lower limb, the prosthetist must ensure the prosthesis swings substantially in the sagittal plane during walking by the patient. In particular if the knee is replaced, it is especially important that the knee flex in the sagittal plane as flexion out of the sagittal plane will grossly exaggerate the patient's lameness due to the prosthesis. During initial fitting the prosthetist may build up an artificial limb utilizing adjustable elements as to length and orientation to the patient's body. However the final prosthetic device is best fixed permanently at the various joints thus precluding further adjustment. This may be done by welding, soldering, brazing or the like. Nevertheless, even with the best initial fitting, the patient, while adapting to the artificial limb, may change his stance or gate to the extent that flexion of the knee joint no longer occurs in the sagittal plane. This is particularly difficult to adjust in a permanently bonded artificial limb particularly when the socket, normally molded to fit the patient's residual limb, is fixed to the remaining portion of the prosthesis. Accordingly, adjustable fittings are available to permit separation of the molded socket from the prosthesis and thus permit incremental rotation of the inferior portion of the prosthesis relative the socket. Available devices are usually affixed to the socket by means such as screws or the like. In some instances the fitting is fixed to a wooden member which in turn is molded to the socket. In either case, release of the fitting is accomplished by loosening the various screws so that an externally splined fitting may be rotated relative an internally splined plate which is fixed for screwing to the socket. Although such a device is serviceable and accomplishes the goal, the devices are relatively heavy and do suffer from the drawback of being fixed to the socket in a manner which can result in failure after repeated adjustments. Finally in any prosthetic device it is always appropriate to decrease the weight of any and all elements in order to decrease the strain placed on muscles of the patient. Therefore elimination of any unnecessary parts and the use of lighter materials to replace other parts is particularly appropriate in the design and use of artificial limbs.